Lennox Hearth CR-3835R Glass Doors, Cold Climate Insulation, FIREPLACE FINISHES Mantels and Trim

18

Glass Doors

If glass doors are to be installed on these fireplaces, refer to specific installation instruc- tions packed with the glass doors. Use only the doors that are listed for use with these fire- places. Use of other non-listed glass door on these fireplaces may constitute a potential fire hazard and is not recommended.

CAUTION: CERTAIN GLASS DOORS OVERLAP THE BLACK METAL FACING OF THE FIRE- PLACE. IF THE FIREPLACE HAS BEEN FACED WITH NONCOMBUSTIBLE MATERIALS, THERE MIGHT NOT BE SUFFICIENT CLEARANCE TO INSTALL THE GLASS DOORS OF YOUR CHOICE. ENSURE ADEQUATE CLEARANCE IS MAINTAINED AT ALL TIMES SO AS NOT TO INTERFERE WITH THE INSTALLATION AND OPERATION OF GLASS DOORS.

COLD CLIMATE INSULATION

If you live in a cold climate, it is especially important to seal all cracks around the fire- place opening with noncombustible material and wherever cold air could enter the room. Surrounding materials must be caulked where it meets the black metal facing of the fireplace to avoid cold air intrusion. Use noncombus- tible caulking material only on fireplace facing to seal. Also, the outside air inlet duct should be wrapped with noncombustible insulation to minimize the formation of condensation. Do not place insulation materials on top of fire- place or against chimney sections.

Note: A 2" air space must be preserved for all combustible materials extending for any con- tinuous length adjacent to the chimney.

It is especially important to insulate between the studs of an outside chase cavity and under the floor if the floor is above ground level. Do not place insulation directly against the fire- place or chimney system.

FIREPLACE FINISHES

Mantels and Trim

It is sometimes best to frame your fireplace after it is positioned and the chimney is in- stalled. Frame enclosure for chimney and fire- place with 2 x 4’s (or heavier) lumber.

Note: The header may rest on the two (2) metal top spacers on top of the unit but the header must not be notched to fit around the spacers.

Note: Only non-combustible wall finishing materials are allowed on the front top of the unit, from the top edge of spacers down. (See Figures 41 and 42 ).

These fireplaces may sit directly on a combus- tible surface. A 2" air space is required be- tween combustible framing and the chimney. A 1" air space is required between combustible framing and fireplace outer wrapper. In Canada, the minimum height for a combustible mantel is 18" (457 mm) above the fireplace opening. Figure 41 shows typical Canadian installa- tions. For installations other than Canada, combustible mantels and trim may be in- stalled 12" above the fireplace opening as per NFPA 211, Section 7-2.3.3. and Figure 42. If a mantel is of a noncombustible material, it is exempt from these requirements as long as it does not interfere with the installation or op- eration of glass doors.

Finished

Wall Header

8" Max. (203mm)

Combustible Mantel

Spacer

18" Min. (457mm)

Fireplace

Opening

Canadian Installation

Figure 41

Finished Wall	Header
12"
Max.
	1 1/2"
Combustible
Mantel
and Trim	Spacer
12"*
Min.
8 3/8"*

Fireplace

Opening

*Both Of These Dimensions Must Be At Least 18” When An Unvented Gas Log Set Rated At 26,000 BTU Or Higher Is Used. (Maximum 40,000 BTU)

Typical Installation

Figure 42

NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.

Hearth Extensions and Wall Shields

A hearth extension must be installed with all fireplaces. It is to protect the combustible floor in front of the fireplace from both radiant heat and sparks. The hearth extension must extend 8" beyond both sides of the fireplace opening and 16" beyond the front (see Figure 43 ). Use a hearth extension constructed of a durable noncombustible material having an equal or better (lower k value) insulating value of k = .84 BTU IN/FT2 HR ° F or a thermal resistance that equals or exceeds r = 1.19 HR

°F FT2/BTU IN. With these values, determine the minimum thickness/material required us- ing the formula and Page 19.

Note: Any noncombustible material whose k value is less than .84 or whose r value is more than 1.19 is acceptable.

If the fireplace is installed on a combustible floor, use the metal safety strips (provided) on the floor extending half under the fire- place and half under the hearth extension (refer to Figures 6 & 7).

A wall shield is required where a continuous perpendicular side wall is within 12" of the fireplace opening (Figure 44 ). Use a 40" W x 40" H wall shield constructed of a durable, noncombustible material having an equal or better (lower k value) insulating value than k =

.84 BTU IN/FT2 HR ° F. At no time may a perpendicular side wall be located closer than 8" from the fireplace opening. See Figure 46.

If fireplace is installed diagonally across a 90° corner; no wall shields are required.